China is facing an increasing social security burden with the rapid growth of its ageing population, a senior official said on Tuesday in Beijing.

The ratio between active employees and the retired will reach 2.5 to 1 by 2020, said Li Bengong, executive deputy director of the China National Committee on Ageing.

In 1990, it was 10:1 and rose to 3:1 in 2003, posing a "great challenge" to the social welfare system, Li told a press conference.

A white paper issued on Tuesday by the State Council Information Office said that at the end of last year, China had nearly 144 million people aged over 60, accounting for 11 per cent of its population; and the number is rising by 3 per cent every year. [full text of the white paper]

In 1982, the number of elderly people accounted for 5 per cent of the total population; but in 1999, the figure reached 10 per cent of the total.

Li said the number of elderly people is expected to reach 248 million by 2020, and 437 million by 2051. The ageing population at the end of the first half of the century will account for a fifth of the world's total, according to estimates by the United Nations.

"The demographic change from an 'adult society' to an ageing society took only 18 years in China, compared to decades or even hundreds of years in developed countries," he said.

In the United States, those aged 65 or above accounted for 12 per cent of the population in 2004.

The white paper said the number of people participating in the basic old-age insurance scheme across the country last year reached 175 million, 43.67 million of whom were retirees. But millions more, especially in rural areas, have no welfare guarantees.

The soaring number of senior citizens has also brought challenges to the health and medical system Li said medical resources consumed by the aged were three to five times higher than other age groups.

"As the number of the aged increases, the expenditure on basic medical care is also growing rapidly."

Li said China has 16 million people aged over 80, many of them living without children nearby. "The demands for efficient social care for this group is great."

The current life expectancy is 72 years, compared with 49 years in 1950.

A survey showed 5 per cent of 144 million aged people, or about 7 million, wish to live in nursing homes. However, at the end of 2005, only 1.5 million beds were available at various care centres. The government said it will add 2.2 million extra beds for the aged in rural areas and 800,000 for urban residents within the next four years.

To channel funds for medical care, China has been piloting a co-operative medicare programme in rural areas since 2003.

By last June, the programme covered 495 million rural people, including 73 per cent of the elderly.

Outlays for the pension fund reached 350 billion yuan (US$43 billion) in 2004, a rise of 66 per cent from 2000.